TAIPEI, Taiwan – A pilot of TransAsia Airways Flight 235 said "mayday, mayday, engine flameout" moments before the propjet banked sharply and crashed into a river, an aviation official said Thursday, but declined to comment on a possible cause for the accident.

Engine flameout refers to flames being extinguished in the combustion chamber of the engine, so that it shuts down and no longer drives the propeller. Causes of a flameout could include a lack of fuel or being struck by volcanic ash, a bird or some other object. "Mayday" is an international emergency call.

Video images of the plane's final moments in the air captured on car dashboard cameras appear to show the left engine's propeller at standstill as the aircraft turned sharply over Taipei, with its wings going vertical and clipping a highway bridge before plunging into the Keelung River on Wednesday.

At least 31 people on board were killed, and 15 people were injured, including a toddler and his father. The search continued for 12 people still missing.

An audio recording of the pilot's communications with the control tower at takeoff and during the minutes-long flight were widely broadcast. A Taiwan Civil Aeronautical Administration official who declined to be named confirmed the distress call and its wording Thursday, but did not say how it might relate to a cause for the crash.

About 10 Taipei fire agency divers were looking for any more bodies that may be at the cold river bottom. A crane was used to bring the rear section of the plane to the shore Wednesday night. The fuselage was largely dismantled by hydraulic rescue tools and now lay alongside recovered luggage.

At midday Thursday, about a dozen relatives of Taiwanese victims arrived at the riverbank in the capital to perform traditional mourning rituals. Accompanied by Buddhist monks ringing brass bells, they bowed to the river and held aloft cloth inscriptions tied to pieces of bamboo meant to guide the spirits of the dead to rest.

Police diver Cheng Ying-chih said search and rescue efforts were being hampered by "zero visibility" in the turbid river and cold water temperatures that were forcing divers to work on one-hour shifts.

He said the front of the plane had broken into numerous pieces, making the job all the more difficult.

"We're looking at a very tough search and rescue job," Cheng told reporters gathered on the river bank beside the wreckage where luggage had been removed and placed in neat rows.

The mangled rear part of the fuselage lay upside down, its wings and tail assembly sheared off and multiple holes torn into its side.

Soldiers and rescue workers worked to shore up the bank with sandbags and steel plates in preparation for lifting further wreckage under cloudy skies. Relatives of some of the Taiwanese victims were expected to visit the scene to carry out traditional Buddhist mourning rituals.

The pilots' actions in the flights final moments have led to speculation that they attempted to avoid high-rise buildings by following the line of the river and then banked sharply in an attempt to bring it down in the water rather than crash on land. Taiwan's aviation authority said it had no evidence of that.

Both the administration and the airline, Taipei-based TransAsia Airways, declined to speculate on causes for the crash at about 10:55 a.m. Wednesday near the capital city's downtown airport. The plane's black box was found overnight. The pilots' bodies have not yet been recovered.

The crashed aircraft, which is less than a year old, had once changed an engine, TransAsia Airways Vice President Wang Cheng-chung told a news conference Wednesday. He said the original one was returned to the manufacturer, Pratt & Whitney Canada, after a glitch was found.

"P&WC gave a complete, brand new engine to TransAsia . and installed it for us," Wang said.

The engine was replaced in April before the aircraft went into use, an airline publicist said.

The ATR 72 turbo-propeller jet suddenly banked 90 degrees within two minutes of takeoff and descended on its side into the Keelung River. It clipped a bridge and a taxi moments before the crash, injuring the driver and a passenger.

Relatives of some of the 31 passengers from China will reach Taipei on a charter flight Thursday afternoon. Local television filmed a mainland Chinese man scolding a travel agency for its handling of injured passengers.

The 15 people who survived the crash were pulled from the open door of a relatively unscathed portion of the fuselage which jutting above the river's surface after the crash.

Among the survivors was a family of three, including a 2-year-old boy whose heart stopped beating after three minutes under water. He recovered after receiving CPR, his brother Lin Ming-yi told reporters.

Another ATR 72 operated by the same Taipei-based airline crashed in the outlying Taiwan-controlled islands of Penghu last July 23, killing 48 at the end of a typhoon for reasons that are still under investigation.

ATR, a French-Italian consortium based in Toulouse, France, said it was sending a team to Taiwan to help in the investigation.

The ATR 72-600 that crashed Wednesday is manufacturer's best plane model, and the pilot had 4,900 hours of flying experience, said Lin Chih-ming of the Civil Aeronautics Administration.

The plane has a general good reputation for safety and reliability and is known among airlines for being cheap and efficient to use, said Greg Waldron, Asia managing editor at Flightglobal magazine in Singapore. About 1,200 of the planes are currently in use worldwide.